The majority of tampons now on the market are made from batts of absorbent fibers such as cotton linters, or blends of cotton with rayon and the like, compressed to a self-sustaining form and to a size adapted for easy insertion into the vaginal tract. While these tampons have been generally acceptable for menstrual protection, their limited absorbent capacity for menstrual fluids combined with poor retentive capabilities for such fluids under normal body pressures often require the user to make frequent, and often premature changes, in order to provide satisfactory service.
Accordingly, attempts have been made to improve performance by adding to the tampon other absorbent materials which have much higher fluid capacity and better retention capabilities than the conventional fibers mentioned above, thus permitting tampons to be worn for a longer time period between changes.
In the prior art one can find a number of patents suggesting the use of various of the so-called "super" absorbent materials for such purposes. Representative of such patents are U.S. Pat. No. 3,589,364 Dean et al, U.S. Pat. No. 3,618,607 Ells et al, U.S. Pat. No. 3,669,103 Harper et al, U.S. Pat. No. 3,670,731 Harmon, U.S. Pat. No. 3,678,031 Schoggen, U.S. Pat. No. 3,723,413 Chatterjee et al, and U.S. Pat. No. 3,731,686 Chatterjee. While the teachings in each of these patents appear to arrive at materials which when incorporated in tampon structures do provide higher fluid capacity and retention, these highly desirable characteristics are apparently achieved at the expense of a reduced absorbency rate, i.e. the tampon has a reduced ability to immediately and rapidly take up fluid from the time of insertion into the vagina. A common disadvantage of this prior art appears to be that while the tampons described therein do show an increased total capacity and some retention improvements, these properties often are not efficiently utilized because of an inability to rapidly draw the fluids into the tampon resulting in fluid bypass or early leakage. Thus, even though such tampons are effective when flow is light and/or slow, and the fluid has time to penetrate into the interior of the tampon; at other times when flows are heavy and/or fast, the tampon is unable to completely contain the fluids which will then bypass the tampon and result in undesirable early failure necessitating change without utilizing potential capacity. In such event, the addition of these high capacity materials is detrimental rather than helpful. While this problem apparently is alleviated in some of the teachings by suggesting structures in which the high capacity fibers are segregated from the more economical conventional fibers which do accept fluids readily, or layered between layers of such conventional fibers, no real solution has been found with respect to improving the performance of tampons in which the high capacity fibers are substantially evenly distributed throughout the tampon structure and which is generally more desirable from a manufacturing standpoint.
Another surprising finding was that even though some laboratory bench tests for measuring potential performance of these tampon products, which tests are designed to simulate in-use conditions and use vagina-like devices and various other test procedures described in the prior art, seemed to indicate that the performance of these high capacity materials would be satisfactory in use, actual clinical tests by users during menstrual periods found otherwise.
This invention is directed to a compressed tampon of absorbent fibers having distributed throughout the tampon structure a quantity of high capacity fibers modified to improve their absorbency rate for menstrual fluids without substantially decreasing total capacity and fluid retention capabilities, which tampons show an improved performance in actual use.